In a conventional manner, leaf springs are used at each side of a vehicle to provide the suspension mechanism between the frame of the vehicle and the axle. Leaf springs are used in many applications, and more prominently in pickup trucks and other large trucks. The general configuration of a leaf spring includes an upper leaf spring pivotally fixed at one end to the frame and the other end connected via a shackle to the frame of the vehicle. An axle is mounted at an intermediate point along the length of the spring. The arrangement results in a leaf spring having a generally elliptic contour. Usually, a plurality of leaf springs are mounted in decreasing length under the upper spring. The vertical displacement of an axle allows a leaf spring to flex according to factors such as spring thickness and mounting position. As a vertical force is introduced into the leaf spring configuration, the individual springs are encouraged to slidably engage each other as the elliptical contour flattens out and the displacement force is dampened. The sliding engagement of a first leaf spring and a second leaf spring can result in unpleasant frictional noises.
The frictional noise associated with a leaf spring configuration have been addressed by providing a plastic insert having a disk portion and a stem portion. The stem portion is inserted through an aperture in a first leaf spring and the disk portion is aligned for slidable engagement with an opposing, second leaf spring. This approach reduces frictional noise but also presents drawbacks. Often the paint and sediment associated with the coating on a leaf spring becomes trapped between the insert and the spring resulting in added frictional noise. Further, existing inserts do not engage the leaf spring to which they are mounted as positively as possible.
Thus, it is desirable to provide a textured surface on the face of the plastic insert to facilitate removal of the paint and sediments to prevent the formation of high spots on the spring. It is also desirable to provide an increased retention force from the stem onto the inner wall forming an aperture of the leaf spring.